I saw that trailer yesterday myself... as I monitor the feeds that ANN puts out.
I actually think HSDXD had/has a lot of potential, I quite like the fairly rich, detailed and flexible backdrop and overall universe. I also like several individual characters I wish they would focus on more. Not much a fan of Rias and think the series should focus more on her not exactly being as nice as she comes off, but that is a minor point...
But despite that, the one thing to consistently ruin my view of it is they potentially picked IMHO one of the single worst characters ever in all of anime to do the entire series viewpoint from. Following not just Isse's point of view but also his thoughts is a major deterant to me liking the series.
Having super major important scenes completely disrupted by his thoughts/actions ruins the story flow, ruins the mood, and is quite aggravating.
I keep just wishing either they would change the viewpoint (say, for example, a season from the viewpoint for Sona or focus on Sona's group) or kill Isse off and give the view to someone else in Rias's group... either would work well for me.
I read fan fiction for this series, but almost exclusively it is either crossovers that reduce / replace Isse's role, stories that focus on a different group, or stories that change him so much to make him unrecognizable.
I'll probably still watch the series... but not really looking forward to more Isse.